Comparison of Urine Iodine/Creatinine ratio between Patients following Stringent and Less Stringent Low Iodine Diet for Radioiodine Remnant Ablation of Thyroid Cancer

Roh, Jee Ho; Kim, Byung Il; Ha, Ji Su; Chang, Sei Joong; Shin, Hye Young; Choi, Joon Hyuk; Kim, Do Min; Kim, Chong Soon

Abstract

A low iodine diet (LID) for 1~2 weeks is recommended for patients who undergoing radioiodine remnant ablation. However, the LID educations for patients are different among centers because there is no concrete recommendation for protocol of LID. In this investigation, we compared two representative types of LID protocols performed in several centers in Korea using urine iodine to creatinine ratio (urine I/Cr).
METHODS
From 2006, April to June, patients referred to our center for radioiodine remnant ablation of thyroid cancer from several local hospitals which had different LID protocols were included. We divided into two groups, stringent LID for 1week and less stringent LID for 2 weeks, then measured their urine I/Cr ratio with spot urine when patients were admitted to the hospital.
RESULTS
Total 27 patients were included in this investigation (M:F=1:26; 13 in one-week stringent LID; 14 in two-week less stringent LID). Average of urine I/Cr ratio was 127.87+/-78.52 microgram/g in stringent LID for 1 week, and 289.75+/-188.24 microgram/g in less stringent LID for 2 weeks. It was significantly lower in stringent LID for 1 week group (p=0.008). The number of patients whose urine I/Cr ratios were below 100 microgram/g was 6 of 13 in stringent LID for 1 week group, and 3 of 14 in less stringent LID for 2 weeks group.
CONCLUSION
Stringent LID for 1 week resulted in better urinary I/Cr ratio in our investigation compared with the other protocol. However it still resulted in plenty of inadequate range of I/Cr ratio, so more stringent protocol such as stringent LID for 2 weeks is expected more desirable.